1. Field of the Invention
This invention relates to automatic assembly apparatus, and more particularly to cam-actuated, reciprocating and indexing, multiple-station assembly apparatus.
2. Description of Prior Art
There is an ever increasing demand for automatic assembly devices, including those that through indexing are capable of performing a series of assembly operations. In many multiple-station, automatic assembly set-ups, an individual slideable pick-up unit or so-called pick and place unit is used at each station to move tooling, grasp parts, place parts in tooling fixtures, and so forth. Typically, whenever such multiple-station assembly set-ups were constructed in the past, especially where both vertical and horizontal movements of the pick-up units were required, a cam-actuated oscillator device was used with each pick-up unit to provide the necessary actuation.
Attempts have also been made to use an open cylindrical or barrel cam with multiple cam tracks to simultaneously operate several pick and place units, through the reciprocation of various tool-carrying plates. However, due to the need for proper synchronization of the various plates and associated assembly devices, a multiple surface cam had to be manufactured to extremely close tolerances. If any one cam track was formed slightly out of phase from another track during manufacture, the required synchronization of the associated assembly components was not provided. Any lack of synchronization, especially where pick and place mechanisms and associated tooling are involved, can result in misaligned parts, jammed or broken tooling, and so forth. Thus, mis-manufactured multiple track cams were usually scrapped as they could not readily be adjusted to overcome the unwanted phase differentials in the assembly structures they actuated. Additionally, the use of open cylindrical cams is undesirable because they can not be easily lubricated or protected from contamination, and their life spans can not be reliably predicted.